Excellent!!
Those make great memories you can always cherish.
I was able to do something similar for my nephew a few years ago. He was about 6 years old during his Xmas visit to our home.
So, without telling anyone but my wife, I grabbed my 10 ft ladder early just before daybreak and climbed up on the roof, knowing he was awake in his bed ... waiting (oh, the waiting, remember?
).
I made the clatter of footsteps (nearly fell off in fact!) over his bedroom and then raced across the roof and back down the ladder and tucked it back behind the garden sheds. I was able to sneak back to bed just before he BURST in and yelled I HEARD SANTA CLAUS!! I'll never forget that, and neither will he. By the end of the morning, he had morphed it in his head to ... I SAW Santa Claus and had a full description at the ready. But Santa that morning was buck naked and freezing except for a terry cloth green bathrobe...
And that's how memories & religions get started....